1. Field of the Invention
The present invention relates generally to surgical devices used in diagnostic testing which include a means for introducing or removing material from a body for therapeutic purposes. More particularly, the invention pertains to a diagnostic and guiding catheter apparatus having a means for precisely locating a distal end of the catheter adjacent to an ostium of a preselected blood vessel, so as to facilitate procedures such as angiography and PTCA.
2. Background of the Prior Art
Many common medical procedures require the insertion of a catheter having a preformed distal end into a patient's cardiovascular system. For example, in selective angiography procedures where an area of a preselected blood vessel is investigated, a coronary diagnostic catheter is percutaneously introduced into the cardiovascular system and advanced therein until the distal tip of the catheter is adjacent the selected area. At this point, radio-opaque contrast is injected into a patient's cardiovascular system, and an X-ray image is taken of the subject area of the blood vessel.
Another procedure involving catheterization is percutaneous transluminal coronary angioplasty (PTCA). In the classic PTCA procedure, a guiding catheter (which is similar in shape to an angiography diagnostic catheter although somewhat stiffer) is percutaneously introduced and moved through the patient's cardiovascular system until the distal tip is adjacent a coronary artery ostium. A guide wire is then introduced through the guiding catheter and is advanced into the patient's coronary vasculature until the distal end of the guide wire crosses the lesion to be dilated. A dilation catheter having an expandable balloon on the distal end thereof is then advanced through the guiding catheter over the previously positioned guide wire until the balloon crosses the lesion. At this point, the balloon is inflated to a predetermined size with radio-opaque contrast solution at relatively high pressures (e.g., 4-12 atmospheres) to compress and split the atherosclerotic plaque of the lesion against the inside of the artery wall to thereby dilate the lumen of the diseased artery. The balloon is then deflated so that the dilation catheter can be removed and blood flow resumed through the dilated artery. Conventional catheters and procedures are described in U.S. Pat. Nos. 4,323,071, 4,439,185, 4,468,224, 4,516,972, 4,538,622, 4,582,185, 4,616,652, and 4,638,805, which are incorporated by reference herein.
It frequently occurs that a coronary stenosis is ostial in location. When the distal tip of a diagnostic or guiding catheter is positioned into the ostiurn of an artery with ostial stenosis, blood flowing into that coronary artery may be drastically lowered or obliterated. This condition requires immediate withdrawal of the distal tip of the catheter in order to prevent development of myocardial ischemia, arrhythmias, hypotension, or even patient death. In such cases, if the patient requires coronary angiography, it is generally performed non-selectively by injecting radio-opaque contrast solution into the ascending aorta. Non-selective coronary angiography requires a larger amount of radio-opaque contrast solution and increases the risks of radio-opaque contrast-induced kidney damage. Moreover, non-selective coronary angiography in general gives a poorer assessment of coronary anatomy.
In cases of ostial stenosis requiring PTCA, it is generally necessary to first position the guiding catheter within the ostium as described. However, in order to allow the dilation balloon to be properly positioned in the ostium, it is normally required that the tip of the guiding catheter be pulled out of the ostial stenosis. That is, without preliminary withdrawal ofthe guiding catheter tip from the ostium, the dilation balloon may be partially within the confines of the guiding catheter when properly positioned for inflation relative to the lesion. This means that the balloon cannot be fully inflated owing to the mechanical interference presented by the guiding catheter tip. Normally, several balloon dilations are required before an ostial stenosis is satisfactorily dilated, and after each dilation angiography is performed to assess the result of the proceeding balloon dilation. Therefore, PTCA of ostial stenosis requires multiple insertions of the distal tip of the guiding catheter into the ostium of the artery, with subsequent preliminary withdrawal and positioning of the dilation balloon, inflation of the balloon and angiography. With each insertion of the guiding catheter tip into the coronary ostium, the risks of acute coronary closure and myocardial infarction are increased.
Another common problem experienced with prior guiding catheters is their inability to stay in a position when the distal end of a dilation catheter is advanced across a stenosis. Surgeons have attempted to ameliorate this problem by buttressing the guiding catheter against the opposed wall of the aorta, by deep-seating the guiding catheter tip well into the coronary ostium, or by use of guiding catheters of various distal configurations and stiffnesses. These attempted solutions are not always successful and can themselves cause complications. To give but one example, use of various types of catheters requires withdrawal of guiding catheter(s) and replacement thereofwith new catheter(s) having different curvatures or stiffnesses. This recatherization not only increases the time required for the procedure but may add further arterial trauma. Withdrawal of guiding catheters also necessitate withdrawal of the guide wire and balloon dilation catheter which increases the risk of acute coronary closure and myocardial infarction.
There is accordingly a real and unsatisfied need in the art for improved catheter products which overcome the problems associated with improper guiding catheter tip placement and the tendency of guiding catheters to shift during placement and use of balloon dilation catheters.